In large bowl, cream together sugar, margarine and shortening, then add 1 egg at a time, mixing after each egg.,Sift flour and soda together and add to mixture.,Add the buttermilk and mix well.,Stir in coconut, pecans and vanilla.,Bake in three 9-inch cake pans, greased and floured.,Bake at 350° for 30 to 40 minutes.,______,Cool on rack for 15 minutes.,Frost while still warm.